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In March 2000, the Miami-Dade County Department of Environmental Resources Management(DERM) asked the Florida Department of Health (DOH) if heavy metals in the soil and non-nativeash at the Miami Civic Center property are hazardous to human health. The Florida DOH, througha cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR) inAtlanta, Georgia, evaluates the public health significance of hazardous waste sites in Florida. Thisis the first review of the Miami Civic Center property by either the Florida DOH or the ATSDR.

The Miami Civic Center property is an approximately 3 acre parcel of undeveloped land located at1700 N.W. 14 Avenue in Miami, Miami-Dade County, Florida (Figure 1). The property containedresidences in the 1930s and supported a plant nursery on the northwest portion from approximately1949 until the mid-1980s. By 1986, the residences and nursery had been cleared from the property. The property has been undeveloped land for the last sixteen years. The property is currentlysurrounded by a small residential housing community to the southeast, a high-rise residentialbuilding to the north, a canal to the northeast, and major roads to the south, east and west.

In 1989 and 1990, an environmental assessment found debris (glass, charcoal, metal, concrete) onthe property. This assessment found elevated concentrations of lead and cadmium in the subsurfacesoil. Subsequent environmental assessment in 1998 and 1999 found elevated concentrations of totallead, arsenic and barium in a non-native layer of ash. This ash was approximately 1.0 to 4.5 feetbelow land surface on the eastern portion of the property. According to the Florida Department ofEnvironmental Protection (DEP), this non-native ash may be from an incinerator previously locateda few blocks away.

Because previous investigations collected soil samples in the subsurface, the Florida DOH requestedadditional surface soil (< 3 inches) tests to more accurately estimate potential exposures. People donot frequently come into contact with soil deeper than three inches. This health consultation islimited to a review of the August 23, 2001 soil sampling and analyses conducted by the DERM.

On August 23, 2001, the DERM collected surface soil (< 3 inches) samples from eight (8) locationson the eastern portion of the property (Figure 2). These samples were primarily between the smallresidential housing community to the south and the high-rise residential building to the north, westof N.W. 14 Avenue. The DERM collected the samples along a non-random, walking transect thatextended north along the east side of the small residential housing community, west along the northside of the housing community, north toward the high-rise apartment building, then southeast alongthe canal. The DERM collected these surface soil samples approximately three to four feet from thefences surrounding the residential properties, in areas where children had been documented playing.

According to the DERM, the property consists of an open field with rolling topography, tall grassand few trees. Access is limited by chain-link fence, but is not completely restricted On the dayof the sample collection, the DERM observed a worn vehicle path on the property and bare patchesof soil containing metal and small glass fragments, as well as residential-type refuse. The DERMalso observed domestic chickens and banana trees on residential property to the south along N.W.14 Avenue. The DERM used Quality Assurance procedures to prevent cross-contamination of thesamples. The DERM laboratory analyzed the samples on August 28, 2001, for arsenic, barium,cadmium, chromium, copper, iron, lead, mercury, nickel, silver and zinc.

The Florida DOH calculated ingestionexposure rates for children (the most sensitive population)assuming a "worst-case" scenario of 3 hour exposures per day, 365 days per year, for 30 years. Generally, an exposure rate (also called a daily dose) is given in milligrams of chemical perkilogram of body weight per day (mg/kg/day). A milligram is one-thousandth of a gram (a raisinor paperclip weighs about one gram). A kilogram is about two pounds. The Florida DOH assumedthat children accidentally ingest 200 milligrams of soil per day, as they are more likely than adultsto put their hands and other objects into their mouth on a frequent basis.

Currently the property is covered by a thick layer of grass and weeds, and there is little or no dustbeing generated. In the event that site conditions change in the future, where vegetation is removed,soil is disturbed and contaminated soil becomes airborne as dust, the Florida DOH calculatedpossible future air contaminant concentrations (Risk*Assistant, 1996).

DISCUSSION

The DOH compared the soil/metal analytical results with health-based screening values. Thescreening values or comparison values serve to narrow the focus of the health consultation to thosecontaminants most important to public health. Screening values are very conservative numbers, butdo not necessarily mean that contamination in excess of these values will cause illness.

The concentrations of barium, chromium, mercury, nickel and zinc in surface soil at the Miami CivicCenter property were all below the ATSDR's health-based screening values and thus are unlikelyto cause any illness. Silver was not detected in any of the surface soil samples and is therefore also unlikely to cause illness.

Analytical Results for Arsenic, Cadmium, Copper and Lead

The following table shows the screening values and maximum surface soil contaminationconcentrations:

â€¡ - DEP Soil Cleanup Target Level for copper is calculated for direct contact including ingestion of contaminated soil, dermal contact with the soil and inhalation of chemicals that might volatilize or adhere to dust. The combined impact of exposure to all three routes simultaneously is used to calculate the SCTL (DEP, 1999).

Â§ - DEP Soil Cleanup Target Level for lead is based on EPA's Revised Interim Soil Lead Guidance for CERCLA Sites and RCRA Corrective Action Facilities (#9355.4-12, 1994). This value was calculated with the EPA's Integrated Exposure Uptake Biokinetic Model which takes into account children's likely exposure from more than one source. Research indicates that young children are particularly sensitive to the effects of lead and require specific attention in the development of a SCTL for lead. "Thus, a SCTL that is protective for young children is expected to be protective for older persons as well" (DEP, 1999).

The Florida DOH calculated a dose and compared it to doses of arsenic known to cause illness inpeople. The Florida DOH found that accidentally ingesting arsenic-contaminated surface soil wouldnot cause any non-cancer illness in children. The Florida DOH found that accidentally ingestingarsenic-contaminated surface soil would result in a "no apparent" to low increased risk of skincancer for adults (ATSDR, 2000).

In the future, if the vegetative cover at the property is removed, soil is disturbed, and arsenic-contaminated soil becomes airborne as dust, long term (30 year) inhalation of the contaminated dustfrom this property may increase the risk of stillbirths and cause a moderate to high increased riskof lung cancer.

Cadmium

The cadmium concentrations in surface soil (3 inches) at four of the eight sample locations wereabove the ATSDR's Environmental Media Evaluation Guide (EMEG) screening value for children. Children playing in the surface soil at the Miami Civic Center property may have accidentally eatensmall amounts of cadmium-contaminated surface soil. To estimate children's potential dailyexposure rates, the Florida DOH assumed exposure to the maximum cadmium surface soilconcentration the DERM reported, 20.3 mg/kg.

The Florida DOH calculated a dose and compared it to doses of cadmium known to cause illness inpeople. The Florida DOH found that accidentally ingesting cadmium-contaminated surface soil (3inches) would not cause any non-cancer illness. There is insufficient evidence to determine whetheror not cadmium is a human carcinogen by the oral route of exposure (ATSDR, 1999).

In the future, if the vegetative cover at the property is removed, soil is disturbed, and cadmium-contaminated soil becomes airborne as dust, long term (30 year) inhalation of the contaminated dustfrom this property may cause a moderate to high increased risk of lung or prostate cancer.

The Florida DOH calculated a dose and compared it to doses of copper known to cause illness inpeople. The Florida DOH found that accidentally ingesting copper-contaminated surface soil wouldnot cause any non-cancer illness. There is insufficient evidence to determine whether or not copperis a human carcinogen by the oral or inhalation routes of exposure (ATSDR, 1990).

The Florida DOH calculated a dose and compared it to doses of lead known to cause illness inpeople. The Florida DOH found that accidentally ingesting lead-contaminated surface soil couldcause a decrease in aminolevulinic acid dehydratase (ALAD) activity in humans. The enzymeALAD is important to the production of hemoglobin in red blood cells. There is insufficientevidence to determine whether or not lead is a human carcinogen by the oral route of exposure(ATSDR, 1999).

In the future, if the vegetative cover at the property is removed, soil is disturbed, and lead-contaminated soil becomes airborne as dust, long term (30 year) inhalation of the contaminated dustfrom this property may significantly decrease ALAD activity in humans. It is unclear if a decreasein ALAD activity is directly related to illness (Environmental Health Perspectives, 1998, 2001).

Additional Data Needs

Because testing of this property found elevated concentrations of arsenic, cadmium and lead, theFlorida DOH recommends additional sampling to delineate the extent of contamination of surfacesoil. Additional analyses of surface soil from the Miami Civic Center property should include othercontaminants known to be associated with incinerator ash waste, especially dibenzodioxins anddibenzofurans. The Florida DOH suggests that 8 to 10 more surface soil (3 inches) samples betested to delineate the extent of contamination.

Children's Health Section

The ATSDR and the Florida DOH, through the ATSDR's Child Health Initiative, recognize that incommunities faced with the contamination of their environment, the unique vulnerabilities of infantsand children demand special attention. Children are at a greater risk than are adults for certain kindsof exposure to hazardous substances emitted from waste sites. Because they play outdoors andbecause they often carry food into contaminated areas, children are more likely to be exposed tocontaminants in the environment. Children are shorter than adults, which means they breathe dust,soil, and heavy vapors close to the ground. They are also smaller, resulting in higher doses ofchemical exposure per body weight. If toxic exposures occur during critical growth stages, thedeveloping body systems of children can sustain permanent damage. Probably most important,however, is that children depend on adults for risk identification and risk management, housing, andaccess to medical care. Thus, adults should be aware of public health risks in their community, sothey can accordingly guide their children.

The Florida DOH compared the average blood lead level for children living in the immediatevicinity of the Miami Civic Center property to the average blood lead levels for all children inMiami-Dade County. This "target neighborhood" was defined as an area between N.W. 12 Avenueand N.W. 17 Avenue and N.W. 14 Street and N.W. 20 Street. In 2000, seventeen children living inthis neighborhood had an average blood lead level of 3.05 micrograms per deciliter (ug/dL),compared to an average of 4.34 ug/dL for all children in Miami-Dade County. In 2001, twenty-sevenchildren living in this neighborhood had an average blood lead level of 2.19 ug/dL, compared to anaverage of 3.62 ug/dL for all children in Miami-Dade County. Based on these results, children livingin the vicinity of the Miami Civic Center property do not have an above-average level of lead intheir blood.

Additionally, the Florida DOH used an ATSDR model to predict blood lead levels in children basedon multiple potential lead exposures. This model predicts that blood lead levels of childrencontinuously exposed to lead in the surface soil at the Miami Civic Center property are not likelyto exceed the action level of 10 ug/dL (ATSDR, 1999, Appendix D).

Sensitive Populations

Sensitive populations exhibit a different or enhanced response to contaminants than most personsexposed to the same level of a contaminant in their environment. Reasons may include geneticmakeup, age, health and nutritional status, and exposure to other toxic substances. Children wereused to calculate exposure rates for this health consultation because they are smaller, are more likelyto ingest larger amounts of soil, are more susceptible to contaminants in the environment and were documented as users of the property being assessed.

CONCLUSIONS

The Miami Civic Center property is an "Indeterminate Public Health Hazard". The Florida DOHcannot rule out possible exposure to elevated concentrations of incinerator wastes other than heavymetals. The extent of contamination of surface soil at the property has not been adequatelycharacterized. Future testing of surface soil at the Miami Civic Center property should include notonly more surface soil samples to delineate the extent of contamination, but also additionalanalytical contaminants associated with incinerator ash such as dibenzodioxins and dibenzofurans.

The concentrations of barium, chromium, iron, mercury, nickel, silver and zinc in the Miami CivicCenter property surface soil (3 inches) were all below health-based screening values and thus areunlikely to cause any illness.

Ingesting arsenic-contaminated surface soil is unlikely to cause any non-cancer illness in children. Ingesting arsenic-contaminated surface soil would result in a "no apparent" to low increased risk ofcancer for adults. If arsenic-contaminated soil becomes airborne as dust, long term (30 year)inhalation of the contaminated dust from this property may cause a moderate to high increased riskof lung cancer.

Ingesting cadmium-contaminated surface soil is unlikely to cause any non-cancer illness in children. There is insufficient evidence to determine whether or not cadmium is a human carcinogen by theoral route of exposure. If cadmium-contaminated soil becomes airborne as dust, long term (30 year)inhalation of the contaminated dust from this property may cause a moderate to high increased riskof lung and/or prostate cancer.

Ingesting copper-contaminated surface soil or inhaling copper-contaminated dust are unlikely tocause any non-cancer illness in children. There is insufficient evidence to determine whether or notcopper is a human carcinogen by the oral or inhalation routes of exposure.

Ingesting lead-contaminated surface soil has the potential to decrease ALAD enzyme activity. Iflead-contaminated soil becomes airborne as dust, long term (30 year) inhalation of the contaminateddust from this property may cause a decrease in ALAD activity. It is unclear if this decrease inALAD activity is directly related to illness. There is insufficient evidence to determine whether ornot lead is a human carcinogen by the oral and inhalation routes of exposure.

Children living in the vicinity of the Miami Civic Center property do not have an above-averagelevel of lead in their blood when compared to children living in Miami-Dade County. Also, anATSDR model predicts that children continuously exposed to concentrations of lead in surface soilat the Miami Civic Center property are not likely to have blood lead levels in excess of 10 ug/dL.

The Miami Civic Center Property Health Consultation was prepared by the Florida Department ofHealth, Bureau of Environmental Epidemiology, under a cooperative agreement with the Agencyfor Toxic Substances and Disease Registry. It is in accordance with approved methodology and procedures existing at the time the health consultation was begun.

Debra Gable Technical Project Officer SPS, SSAB, DHACATSDR

The Division of Health Assessment and Consultation, ATSDR, has reviewed this healthconsultation, and concurs with its findings.